<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>123</title>
		<style>
		div.t{
			width:800px;
			height:800px;
			background:antiquewhite;
			
			/* overflow:hidden; */
			border:1px solid blue;
		}
		span{
			/* 子元素碰不到父元素有效的border或者padding */
			display:block;
			width:200px;
			height:200px;
			border:3px solid black;
			background:red url(images/1.jpg) no-repeat center center;
			margin-top:100px;
		}
		</style>
	</head>
	<body>
		<div class="t">
			<span></span>
		</div>
	</body>
</html>